The present invention has to do with that unique form of internal combustion reciprocating engine which is characterized by two or more pair of axially aligned, oppositely disposed cylinders, pistons within the cylinders and a single connecting yoke fixedly secured to and extending between the pistons in each pair of cylinders. The longitudinal axis of each pair of cylinders is angularly related to the longitudinal axis of each of the other pairs of cylinders and intersects and is at right angle to a crank shaft on the central turning axis of the engine.
This invention is further concerned with the above noted form of engine which includes a double isosceles sliding block linkage motion-translating mechanism including a unitary twin eccentric disc driver engaged with and between the yokes of the related pairs of pistons and the crank shaft and which functions to translate the reciprocating motion of the connecting rods into convenient-to-use rotary motion at the crank.
The simplest form of engine of the character referred to above is a four-cylinder engine consisting of two pairs of cylinders arranged with their central longitudinal axes at right angle to each other, in the nature of a "cross". Due to their above-noted configuration, such engines have been appropriately described as "cruciform engines".
In practice, cruciform engines can be made with three or more related pairs of cylinders. In such engines, the basic geometry of the engines remains the same, and they are appropriately defined as "cruciform-type" engines.
The double isosceles sliding block linkage motion-translating mechanism referred to above and which I utilize in my new engine structure functions as and puts to use the same unique linkage that characterizes elliptic trammels. Accordingly, in the following, the motion-translating mechanism that I provide can, for the sake of brevity, be called the elliptic trammel-type motion-translating mechanism.
Cruciform engines with elliptic trammel-type motion-translating mechanisms are known to be old in the art. In the above cited Popular Science magazine article entitled "Esso Research Explores A Radical New Cruciform Engine," an internal combustion cruciform engine with a twin eccentric disk drive part that is understood and believed to be a part of an elliptic trammel-type motion-translating mechanism is illustrated. For the purpose of this disclosure, the engine which is the subject of the noted magazine article will be referred to as the Esso engine.
In the Popular Science magazine article, it is noted that the basic layout of the Esso engine was traced back to about 1886, when Sir Charles Parsons, an Irish engineer of steam turbine fame, applied it to a piston steam engine, the layout of which was said to be "cruciform."
In accordance with the above, it appears well established that cruciform engines with elliptic trammel-type motion-translating mechanisms are old in the art.
In the Popular Science magazine article, the great potential and favorable attributes of and certain advantages afforded by such engines are particularly noted.
In the Popular Science magazine article, the failure of cruciform engines, in any form, to gain acceptance or to attain any notable commercial success is noted, but the cause for such failure is left to speculation.
When researching the prior art and when designing and operating prototype cruciform engines of the character referred to above, I found strong indication that in cruciform engines with elliptic trammel-type motion-translating mechanisms have exceedingly high lateral forces are directed through each related pair of pistons onto the walls of their related cylinders as those pistons reach the ends of their strokes; that is, as one of each pair of pistons reaches Top Dead Center and its other piston reaches Dead Bottom Center. Those high forces having been determined to be such that they generate such great fiction and heat at and between the cylinders and pistons, as the pistons approach the ends of their strokes, that the pistons and/or cylinders are caused to degradate rapidly and are so highly susceptible to premature failure and destruction as to render such engines impractical in the absence of supplemental bearing means to relieve the pistons from excessive lateral or side loading.
My above noted findings appear to be affirmed by the teaching of the above cited Reed H. Grundy patents. Reed H. Grundy makes specific reference to the above noted Popular Science magazine article in which the Esso engine is described. He further discloses an eccentric disc-type motion-translating means with right angularly related pairs of cylinders and related pistons, such as is provided in the Esso engine. Grundy recognized that in such engines excessively high and destructive lateral forces are encountered between the pistons and their cylinders near the ends of the strokes of the pistons. The essence of Grundy's invention is to eliminate the adverse and destructive effects of excessive lateral or side loading of the piston by secondary load transfer mechanisms that serve to direct lateral forces or loads otherwise transmitted through the connecting yokes and directed onto and through the pistons directly onto their related cylinders and/or onto the crank case of the engine and to thereby relieve the pistons from all lateral loading. It appears that Grundy understood and believed that the adverse side loading on the pistons in his and other similar engines was caused by the inability of the crank and connecting yoke structures of such engines to accommodate the loads encountered and resulting lateral displacement and/or deflection thereof. He appears to suggest and teaches that lateral displacement and/or deflection of the crank of his engine caused lateral displacement of the connecting yokes and that lateral displacement and deflection of the connecting yokes resulted in urging the pistons laterally into engagement with their related cylinders with destructive force. To counter the foregoing, Grundy teaches unique primary load carrying mechanisms to intermittently support and prevent displacement of the crank pin of his crank shaft; and, a secondary load carrying mechanism comprising lubricated linear bearing structures at and between opposite side edges of the connecting yokes and spanning the crank case structure of his engine.
In his disclosure, Grundy inaccurately illustrates and ascribes the manner in which the forces in cruciform engines with elliptic trammel-type motion-translating mechanisms are directed. He shows and describes the lateral forces applied onto and through the pistons in a direction opposite to the true direction in which such forces are applied. In the structure he discloses, the link mechanism embodied therein is that of an elliptic trammel and the piston and yoke assemblies are link parts that react with their related cylinders in a direction other than to that which he teaches.
While Grundy's efforts to eliminate the adverse effects of side loading of the pistons in engines of the character here concerned with are understood and believed to be totally ineffective, Grundy's teachings are nonetheless highly significant since they point clearly to the fact that the critical problem of side loading of the pistons in such cruciform engines was a long recognized and yet to be resolved problem as late as 1979. Grundy's teachings also point to the extreme ends that others have undertaken in efforts to overcome the noted problem of excessive side loading of the pistons in cruciform engines and to make such engines practical.